1. Field of the Invention
The present invention generally relates to a method of motion detection, and more particularly, to a method of motion detection using motion information of neighboring pixels.
2. Description of Related Art
With development of multimedia technique, requirement for image quality is substantially increased. The image quality may be influenced by the noises generated during image capturing, signal conversion and signal transmission. Therefore, an image processing technique is required to eliminate the noises that may be sensed by human eyes. The image processing methods for noise reduction commonly include a spatial noise-reduction process and a temporal noise-reduction process.
The spatial noise-reduction process applies a filter to perform spatial filtering process on the pixels of a current frame, so as to smooth and soften the frame, and reduce a visual perception of the human eyes for the noises. However, such method generally leads to image blurs, which may influence the presentation of image details, such as edges and textures, for example.
The temporal noise-reduction process references information of a previous frame, so as to perform temporal filtering process to the pixels of the current frame. Since the current frame is highly related to the previous frame, the temporal noise-reduction process can maintain and reserve details of the frame. However, when the temporal filtering process is performed on a moving object within the frame, motion blurs may occur on the edges of the moving object. Therefore, a motion detection algorithm is provided to detect the moving pixels in the frame, so as to adjust an intensity of the temporal filtering for eliminating the motion blurs.
Generally speaking, motion detection uses differences between corresponding pixels in the same parity field to determine whether the designated pixels are moving pixels or not. If the difference is larger than a preset threshold, it means a variation is occurred in the content of the video and the corresponding pixels are determined as the moving pixels. On the other hand, if the difference is smaller than the preset threshold, it means no variation is occurred in the content of the video and the corresponding pixels are determined as the static pixels.
Through the motion detection as described above, motion information of pixels of the moving object is obtained and referenced for determining whether to use a spatial interpolation or a temporal interpolation method to generate the required frame data, in which the temperal interpolation is used for calculating values of pixels in an area with no moving object and the spacial interpolation is used for calculating values of pixels in an area with moving objects.
As described in the above, the motion detection algorithm is complicated and requires a large amount of calculation. If the moving object is mistakenly detected as a static object, the pixels thereof will be calculated through the temporal interpolation method and accordingly serious noises will be generated. Therefore, there is a need to increase the correctivity of motion detection while reducing the size of the buffer needed for storing the reference motion information.